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in DIAdem Time Step in Generate Time Channel how is "Time step" defined?

I am trying to obtain a contour map of orders vs rpm vs magnitude of an acceleration signal. I ported the .tdms files of acceleration response, "current speed" and voltage channel containing a tach signal into DIAdem.


I used the time stamp to define the beggining and end of the current speed file to create the Time channel. When I click the calculate button in the Order Analysis in the Frequency Domain pop up window I get a maessage that says"The start value 1 for the rpm reduction is too low. It must be greater than or equal to 102.48."


Where did that number come from? What is a "Time step"?  Should I be using the "Voltage.tdms (tach channel signal) to generate the Time channel instead of "current speed.tdms"?


What is Start value, End value, and Step width? My measurements start at near 0 rpm and end somewhere around 1300 rpm, but if I use these values for the Start and End values, I get a message that says, "The end value for the rpm reduction is too high. It must be less than or equal to 4.86." I have no idea where 4.86 comes from.

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Message 1 of 5

Hi VW55, 


Before we talk about your other questions, we need to figure out how your data is organized. Do you know if it is organized as waveform data or numeric data. Numeric data is just a channel of data, whereas waveform data includes an x and y component. The x component generally contains time data that refers back to the y part (data). Here is a document about waveform data: http://zone.ni.com/reference/en-XX/help/370859J-01/genshell/genshell/genshell_waveforms/

This means that if your data is numeric you would need to create a separate time channel to use some analysis functions. If your data is waveform data you do not need to create a separate time channel.

After we clarify this, we can then work through your other questions.

Rachel M.
Applications Engineer
National Instruments
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Message 2 of 5

Hi VW,


Given the desired outcome you describe, I would encourage you to use the posted "Joint Time Frequency Analysis Tool", which you can find here:




Brad Turpin

DIAdem Product Support Engineer

National Instruments


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Message 3 of 5

pam pwm converter circuit such errors 

time site method 


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Message 4 of 5

Hi ikumbet,

This forum thread is several years old and appears to be a different topic than you are bringing up. 


Please post as a new thread on the DIAdem discussion forums and please include more context about your program and what is happening that is resulting in these errors.




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Message 5 of 5